NVMe: The networked future for insatiable data access speeds

NVMe’s no longer just a protocol for fast flash drive connections to a PC via the PCI Express bus. Discover the future of NVMe usage here, including exclusive details on how the M.2 SSD form factor is approaching server-ready capacity and speed.

PCIe form factors and use cases

Format specifications for PCIe-based devices are developed and maintained by the PCI Special Interest Group (PCI-SIG). The current version, PCIe 3.0, was released in November 2010. PCIe 4.0 is slated for release in 2017.

Example of a PCIe SSD.

Support is emerging for PCIe SSDs designed for the nonvolatile memory express (NVMe) specification. The NVMe protocol provides an optimized command set for accessing a PCIe SSD. NVMe exploits the parallelism of PCIe 3.0 to accelerate performance.

This video explains the differences between ATA, M.2, PCIe and NVMe form factors.

The PCI-SIG also authored standards for M.2 SSDs, a small form factor designed for internally mounted expansion cards. The M.2 specification replaced the mSATA form factor. M.2 SSDs are equipped with four lanes of PCIe 3.0 bandwidth.

PCIe SSD vs. SATA SSDs

As previously discussed, PCIe-attached SSDs avoid the bottlenecks associated with SATA or SAS-attached SSDs. The number of PCIe lanes per SSD determines the speed of data transfer. A 16-lane device built on the PCIe 3.0 specification can support approximately 32 gigabytes per second. By contrast, SSDs built with a SATA III controller provide a maximum transfer rate of about 600 megabytes per second.

PCIe drive vendors have moved only gradually to implement the 3.0 specification. Most vendors are still shipping products based on PCIe 2.0.

The SATA v3.2 specification defines SATA Express connectors for host and device connectors that simultaneously support SATA and PCIe protocols.

PCIe SSD drawbacks

The PCIe multipurpose bus carries varied data to the processor. Despite its inherent performance benefits, PCIe SSDs have a higher cost per gigabyte than traditional SSDs.

The lack of standard storage commands is another drawback. PCIe SSD device makers are required to write and qualify a custom software driver for operating systems.

The future of PCIe flash

For the foreseeable future, PCIe flash figures to coexist in enterprise data centers with traditional SSDs and nonvolatile memory technologies.

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